Examine source code of HouseHunter

{
  "manifest_version": 2,
  "name": "HouseHunter",
  "version": "1.0",
  "description": "Helps with house hunting on some real estate sites",
  "icons": {
    "48": "house48.png"
  },
  "permissions": [],
  "content_scripts": [
    {
      "matches": [
        "*://*.redfin.com/*"
      ],
      "js": [
        "js/househunter.js"
      ]
    }
  ]
}